In the past several years, many unexplained failures have occurred in turbomachinery particularly in compressors, turbines, generators, pumps and the like in high performance, high speed installations. Such failures may be for example damage to bearings and bearing shoes and seals and where a spark jump may occur between rotating and stationary parts. This damage frequently results in destructive damage causing plant shutdown. This damage has been found in many cases to be the result of magnetic currents generated by residual magnetic fields in either stator or rotor components. The problem has become greater as magnetic tools become stronger and are more widely used both in manufacturing and repair. Much electric arc welding is now being done around these types of machines and currents created travel through casing and rotor leaving magnetic fields that may be very strong. When the machinery with these residual magnetic fields is put into operation and the rotor begins to turn electric voltages and currents are generated in the same manner as in an electric generator and the strength of these voltages and currents depends on the strength of the residual magnetic fields and their relationship to one another, the clearances and masses involved, the speed of the rotor, the available paths for the currents and insulated properties of the oil film. Self-excitation may occur as the currents and fields line up with the result of rapid failure of the machinery.